Help printing inside threads

When I print inside threads of 20mm or less, The support material is formed like a spider web. Where it sticks to the threads, it is fully melted in and removes the thread when the support is removed. The same printer settings work OK with same pitch thread but 35mm diameter. I've slowed the printer to 30mm/s and am printing support for 45 degr overhang or more. The rest of the part is OK, just the threads get mangled when removing the support material. Temp is 230C height is .20mm, nozzle is .35mm, printer is Lulzbot TAZ.

< has never been able to print threads
sorry

Is that file something on thingiverse? I'll give it a shot and see if I can and what settings.

I had always had some issues with inside threads and support but not stringing like this. Do you have a retraction set? I would do at least 2mm retraction and see if it helps.

One time I tried threads with no support and it worked better than I thought but it depends on the pitch and depth of the threads.

This is a part from a design I'm working on. The threads are .875 x 20 tpi. I have tried 0, 1 and 1.6mm retraction. I'll try 2. Also going to try changing the options for the support material. Will try 1mm pattern spacing and .1mm Interface pattern spacing. Doesn't seem to be any difference between honeycomb and rectilinear for support pattern. Maybe that only affects the raft?

Forgot to mention that a buddy printed a very clean part with good threads from his Affinia, also from ABS. I can't seem to get the threads as good as his because of the support, but the rest of my part is as good or better.

I've printed parts on an Up! with both external and internal threads, and had great success (I haven't tried yet on my MendelMax). On the Up!, I did NOT use support material. Looking at your picture, I suspect you could probably print this part without support material and have it turn out better.

try using cura progam or kissslicer. they have better clean up on strings.

Assuming that your printer is correctly calibrated, IMHO there is something to tweak in your geometry.

So far I've been printing parts with 6mm threaded holes (to hold the PFA bowden tube) succesfully.
I am no wizard (and LOTS of people out there beat my skills hands down) therefore just keep trying and refining your STL.

For smaller threads, I've been cheating a bit: a cross section of my threaded holes reveals a trapezoidal pattern (to avoid having a single brittle layer hanging on the inside of the hole) to get a cleaner and stronger part.

Using Slic3r 09.10b.

Keep tryin' !

Bye
Davide

Edited 1 time(s). Last edit at 07/18/2013 02:56AM by 3ntrlab.

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no toys here...sorry

I would double check your E calibration. When the extruder calibration is a little thin that happens on smaller holes. Print a single wall width part and measure the wall width to make sure its what its suposed to be.

Success!
I printed without support and the problem persisted. I increased the extrusion rate by 10% so the material wasn’t being stretched as it was laid down. That allowed the material to stick where it was placed. I didn’t use support material. Picture is of before and after. Thanks to those who had input.